* MAMEUI's handling of DAT files has nothing to do with MAME, no code is shared.
* In the menu, Options -> Directories -> DAT files -> is where DAT files should be stored.
* The only DAT files supported are: gameinit.dat, history.xml, messinfo.dat, mameinfo.dat, command.dat
* The list is hard-coded and users cannot add more.
* There's no history.db, but there's an equivalent history.idx . There's no support of adding more DATs via LUA script or any other means.
* Plugin.ini is not used - the selected plugins are stored in mame.ini -> plugin (this idea is supported by MAME).